In magnetoresistive memory cells and in processes for producing them, a first, lower or bottom electrode device and a second, upper or top electrode device, with a tunnel barrier region between them, are provided in this order as storage element. The first, lower or bottom electrode device is formed with a hard-magnetic reference region having a region comprising or consisting of a natural antiferromagnet.
In operation, depending on the orientation of the magnetizations of the hard-magnetic reference region and of the soft-magnetic storage region of the top electrode device, a tunneling resistance, which is dependent on this mutual orientation of the magnetizations, can be determined by measuring a flow of current between the bottom electrode and the top electrode when a potential is applied and can be used to derive an information state or memory content, is established between the bottom electrode and the top electrode via the tunnel barrier region.
Important requirements for magnetoresistive memory cells are firstly magnetic coupling or interaction which is as direct as possible within the hard-magnetic reference region and/or the individual layers of the hard-magnetic reference region with respect to one another and magnetic coupling which is as weak as possible in the transition region between the hard-magnetic reference region and the soft-magnetic storage region, i.e. in the tunnel barrier region, by which the tunneling resistance is substantially defined.
At the same time, a magnetoresistive memory cell, and in particular the arrangement of the various layers provided as the storage element, should have the minimum possible geometric dimensions, so that the minimum possible amount of space is lost and therefore a high integration density can be achieved. Furthermore, it is also intended to ensure a particularly long operational reliability and data retention time.
In known magnetoresistive memory cells, however, it has been found that it is difficult to satisfy all these conditions simultaneously.